Requests the LightClientUpdate instances in the sync committee period range [start_period, start_period + count), leading up to the current head sync committee period as selected by fork choice. Depending on the Accept header they can be returned either as JSON or SSZ-serialized bytes.

Servers SHOULD provide results as defined in create_light_client_update. They MUST respond with at least the earliest known result within the requested range, and MUST send results in consecutive order (by period). The response MUST NOT contain more than min(MAX_REQUEST_LIGHT_CLIENT_UPDATES, count) results.